1. Field of the Invention
This invention relates to an image sensing apparatus having an electronic monitor and means for changing a manner in which an image sensor, etc. are driven and a manner in which power supply is effected to peripheral circuits when the apparatus is in a monitor mode.
2. Description of the Prior Art
The image sensing apparatuses such as electronic cameras are highly promising apparatuses capable of replacing the cameras of the kind using silver halide. However, they have some basic problems. The first of such problems relates to power consumption. In intermittently taking still pictures, the power consumption presents no serious problem. However, in cases where an electronic monitor is connected to or mounted on the camera in particular, an image sensing system or a reproducing system must be kept continuously driven for continuous monitoring or play back. Such a requirement then presents a grave problem in connection with power consumption.
A second problem relates to the performance of the electronic monitor such as the resolving power of the monitor. An insufficient resolving power of the monitor would bring about a spurious resolution or the like when an image signal is monitored through the same signal processing arrangement as in recording or reproduction. Further, in case that the monitor does not possess an adequate power in relation to the image sensing or recording power, that is, in cases where the monitor is for a black-and-white signal while the image sensing or recording signal is a color signal or where the reproduction band of the monitor is narrower than the image sensing or recording band, there arises a loss of electric energy and degradation of picture quality.
A third problem with the prior art apparatuses lies in the relation between the resolving power of the monitor and the manner in which the image sensor is driven. Heretofore, a monitoring image signal has been obtained by driving an image sensor in the same manner as in recording or reproduction. A monitor device is thus required to have a high degree of performance. Particularly, the resolving power in the vertical direction of the monitor is required to be equal to that of the image sensor. The monitor arrangement of the prior art thus has resulted in a high cost.
Whereas, no particular attention has been paid to these problems in the image sensing apparatuses of the prior art such as electronic cameras, facsimile devices, copying machines, etc.